Elevator systems



June 11, 1957 w. F. EAMES 2,195,295

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United States Patent house Electric Corporation, East Pittsburgh, Pa., a corporation of Pennsylvania Application July 15, 1954, Serial No. 443,618

45 Claims. (Cl. 18729) This invention relates to elevator systems which are automatically modified to provide different modes of operation and it has particular relation to elevator systems having graduated responses to graduated variations in service demand.

It is well known that the demand for service from an elevator system in the average building varies appreciably throughout the day. For example, during the night in an oflice building the elevator system usually is required to provide very little service. This period is referred to as an off-hours period of operation.

At the start of a business day a substantial demand for service in the up direction from the lower terminal floor occurs. This period is known as an up-peak period. A similar period often occurs immediately following the lunch hour.

Immediately prior to the lunch hour and after the close of the business day a peak demand for down service generally is encountered. Such periods are designated down-peak" periods.

During the remainder of the business day the demand for elevator service in the two directions of travel is substantially balanced. Such periods are known as offpeak periods. I In accordance with the invention an elevator system is provided with a gradual change in the mode of operation to accommodate a gradual change in the service demand. The gradual change in the mode of operation may be effected by computing or selecting means such as a time clock which provides each mode of operation at the desired time of the business day. However, in a preferred embodiment of the invention the variation in the mode of operation is effected in response to the demand for elevator service.

Thus in response to a gradual increase in the demand for down elevator service the carrying capacity of the elevator system in the down direction is gradually increased. This increase may be at the expense of the service in the up direction. However, during the downpeak periods the demand for up service is generally small. Consequently, the invention provides increased efliciency in the overall performance of the elevator system.

Although aspects of the invention are applicable to elevator systems employing only a single car, the invention is particularly suitable for systems employing a plurality of elevator cars and will be discussed with reference to a multiple car elevator system. For purposes of illustration it will be assumed that during otf-peak periods the elevator system is conditioned to operate each elevator car on through trips between terminal floors or landings.

In order to determine the extent of the need for elevator service in a given direction suitable computing mechanism is provided. For example, the demand in the down direction may be determined by the number of down floor calls or by the number of priority down floor calls. A priority down floor call is a down floor call which for some reason is entitled to greater weight than 2,795,295 Patented June 11, 1957 other down floor calls. For example, a down floor call which has been registered for more than a predetermined time such as 40 seconds may be considered to be a priority down floor call. Alternatively a call from a certain floor may be considered to be a priority down floor call.

In response to a small demand for service in the down direction as represented by a small number of down floor calls or a small number of priority down floor calls, the elevator cars of the system may be arranged to reverse when traveling in the up direction at the highest fioor or landing for which a call is registered provided the call is not an up floor call.

If the demand for service in the down direction increases to what may be termed a moderate demand as represented by a somewhat larger number of registered down floor calls or priority down floor calls, certain or all of the elevator cars of the bank may be prevented from responding to up floor calls.

it the demand for elevator service in the down direction increases still further to what may be termed a heavy demand, the carrying capacity of the elevator system in the down direction may be still further increased. For example, the floors served by the elevator cars may be divided into zones and certain elevator cars may be assigned to serve each of the zones of floors.

As a final example, if the demand for service in the down direction increases to what may be termed an extreme demand, the elevator cars may be assigned to respond only to priority calls.

From the foregoing discussion it is clear that as the demand for elevator service in one direction gradually increases, the capacity of the elevator to provide such service is gradually increased. In the preferred embodiment of the invention the reverse is also true. As the demand for elevator service in the given direction decreases, the capacity of the elevator system to provide such service is gradually decreased.

The operation of an elevator system during an uppeak period now will be considered. This demand is computed by measuring a function of the registered car calls. For example, if the registered car calls exceed a predetermined number, the carrying capacity of the elevator system in the up direction may be automatically increased by assigning part of the elevator cars during up travel to reverse at the farthest floor in the up direction for which a call is registered. Such cars may be prevented from responding to up floor calls. If the registered car calls exceed a predetermined larger number all of the elevator cars may be assigned to reverse at the highest floor for which a car call is registered and the elevator cars may be prevented from responding to all floor calls.

If an elevator car makes a large number of stops during a trip between terminal floors, the elevator car may be substantially delayed in reaching its destination and passengers within the elevator car may complain ofthe slow service. In accordance with the invention the movement of the elevator car may be expedited under such conditions.

If the elevator car is traveling towards the lower terrninal floor, the delay may be measured conveniently by computing the duration of registration of a car call for the lower terminal. If this duration exceeds a predetermined value, the movement of the elevator car may be expedited by preventing it from responding to registered down floor calls. If desired, such bypassing may be permitted only if the registered down floor calls are below a certain number. The bypassing also may be permitted if the duration of the car call for the lower terminal floor exceeds a predetermined value and the elevator car is passed by another elevator car traveling in the down direction even though a large number of down floor calls may be registered.

I It is therefore an object of the invention to provide an elevator system wherein the capacity of the elevator system to handle traffic in a predetermined direction is gradually increasedin response to predetermined conditions.

It is a further object of the invention to provide an elevator system wherein the capacity of the elevator system to handle traffic in a predetermined direction is graduallyincreased in: response to a gradual increase in the demand for elevator service in such direction.

It is: an additional object of the invention to provide an'- elevator system wherein the mode of operation of the elevator system is responsive to registered car calls.

It is another object of the invention to provide an elevator system wherein movement of an elevator car is: expedited in response tofailure of the elevator car to deliver: passengers with reasonable promptness.

Other objects of the invention will be apparent from the following description taken in conjunction with the accompanying drawings in which:

- Figure I is: aschematic view with circuits shown in straight-line form of a portion of an elevator system embodying the invention;

Figs. 2 to 5' are schematic views with circuits shown in straight-line form of further portions of the elevator system illustrated in Fig. 1; and

Figs. 1A to 5A, respectively are key representations of relays and switches illustrated in Figs. 1 to 5. If Figs. 1A to are horizontally aligned respectively with Figs. 1- toS, it will be found that corresponding contacts and coils of relays and switches shown in the horizontally aligned figuresare substantially in horizontal alignment. In some cases involving groups of similar relays only representative relays are shown in the key representations.

In order to facilitate the orderly presentation of the invention, a; number of conventions have been adopted. Although the invention may be incorporated in an elevator system'having any desired number or elevator cars serving a structure having any desired number of floors or landings; it will be assumed that the invention is incorporated in an elevator system having three elevator cars serving a structure having six floors or landings. The elevator cars are designated by the reference supporters A, B and C. Inasmuch as the circuits associated with the-three elevator cars are similar, it will suffice to show primarily the circuits associated with the elevator cars A and B. However certain components associated with the elevator car C also will be referred to.

B'ecauseof the similarity of'tlie circuits and components associated with the three elevator cars, compenents associated with the elevator cars B andC will be identified by-the same reference characters employed for the cornponen'tsz associated with the elevator car'A preceded by the appropriate letter B or C. For example, the resistors R8, BR8-and CR8 are associated respectively with the elevator cars A, B and C. Consequently the discussion" will be directed primarily to the elevator car A and its circuits. 7

Relays and switches employed for the elevator system may have front or make contacts and back or break contacts. Front or make contacts of a relay are closed when the relayis energized and picked up. The contacts are open whenthe relay is deenergized and dropped out. Back or break contacts of a relay are closed when the relay is deenergized and dropped out. The back or break contacts are open when the relay is energized and picked up.

Each set of contacts of a relay or switch is designated by' the reference characters employed for the relay or switch followed by a suitable numeral specific to the set of contacts. For example, the reference characters U1 and U3 designate the first and third sets of contacts respectively associated with the up switch U of the ele- 4 vator car A. In the drawings all relays are shown deenergized.

In order to further facilitate the presentation of the invention, certain apparatus specific to car A and certain apparatus common to all of the elevator cars are set forth as follows:

APPARATUS FOR CAR A E-Inductor slowdown relay FInductor stopping relay 'V-Speed relay HHigh-zone car relay L-Low-zone car relay SE-Timed floor call stopping relay J-Reversa] relay PDPass' relay SST-Stop time relay APB-Relative position relay "FA-First timing relay TB-Second timing relay APPARATUS COMMON TO ALL CARS IUR to 5UR-Up floor call registering relays ZDR to 6DRDown floor call registering relays HCMBank high call reversal relay DSEFirst down service demand relay EM-Second down service demand relay 2CC, 3CC, 4CC, 5CCDown call quota relays 1T, 2T, 3T, 4T-Timed call relays HCR-Second car-call quota relay MHCRFirst car-call quota relay 300- First selection relay SOL-Second selection relay ZDRT to GDRT-Floor-call timing relays USE-Modifying relay Figure 1 Fig. 1 shows the elevator cars A and B' and certain control circuits associated-therewith. Theele'vato'r' car A will be assumed to be stopped at the second floor of the structure whereas the elevator car B will be assumed to be stopped at the fifth floor of the structure. With these exceptions, the circuits and mechanisms associated with the two elevator cars are similar and will be uuderstood by reference to those associated with the elevator car A. Circuits for the elevator A are shown in the left-hand column of Fig. 1.

The elevator car A is connected by a rope or cable 10 to a counterweight 11. The rope 10 passes over a sheave 12, which is secured to a shaft 13 for rotation therewith. The shaft 13 is rotated by a motor 14 which may be of any conventional type. For present purposes it will be assumed that the motor 14 is a direct current motor hav ing its armature 14A secured to the shaft 13 and having a field winding 14F which is permanently connected across two direct-current buses L1 and L2 which supply direct current'energy for the control circuits.

The elevator car'A hastherein a plurality of normallyopen car-call push buttons 10 to 60 which are actuated for the purpose of registering calls respectively for the arm.

first to sixth floors as desired by passengers entering the, elevator car.

To permit registration of calls for service by prospective passengers located at the various floors served by the elevator cars, push button stations are located at such floors. Such a station is shown in Fig. 1 for the third floor. It includes a normally-open up floor call push button 3U which is pressed by a prospective passenger desiring elevator service in the up direction. A similar push button is located at each floor from which service in the up direction may be desired. The station also includes a normally-open push button 3D which is pressed by a prospective passenger desiring elevator service in the down direction. A similar-push button is located at each floor from which elevator service in the down direction maybe desired. The numeral of the reference characters (as 3D or 3U) indicates the floor at which the push button is located.

The elevator car A also has mounted thereon a slowdown inductor relay E and a stopping inductor F which may be of conventional construction. The slowdown relay E has two sets of break contacts E1 and E2 associated therewith. The relay has a normally incomplete magnetic circuit and initial energization of-the winding of the relay alone does not initially open the associated contacts. However, if the slowdown relay E reaches an inductor plate UEP located in the hoistway of the elevator car while the winding of therelay is energized, the cont'acts E1 open. The inductor relay may be of the type which when it opens the contacts maintains the contacts open until the relay winding is deenergized even though the relay passes beyond the inductor plate. In Fig. 1 the inductor plate UEP is assumed to be mounted in the hoistway to be reached by the slowdown relay E as the elevator car A nears the third floor. If the elevator car A is to stop at the third floor, the winding of the relay E is energized and when the relay reaches the inductor plate UEP for the third floor, the contacts E1 open to initiate a slowdown operation for the elevator car. It will be understood that a similar inductor plate is similarly associated with each of the floors at which the elevator car A may stop during up travel thereof.

During down travel of the elevator car A, the inductor relay E cooperates with down inductor plates DEP to initiate a slowdown of the elevator car as it approaches a floor at which the elevator car is intended to stop. For example, if the elevator car is to stop during down travel at the third floor, the winding of the inductor relay E is energized as the elevator car nears the third floor. When the inductor relay reaches the down inductor plate DEP for the third floor, the contacts E2 open to initiate a slowdown operation of the elevator car. It will be understood that a similar inductor plate DEP is provided for each of the floors at which the elevator car A is to stop during down travel thereof.

The stopping relay F similarly cooperates with inductor plates UFP and DFP for the purpose of bringing the elevator car to a stop as it reaches a floor at which it is to stop. Thus, if the elevator car A during up travel is to stop at the third floor, the winding of the stopping relay F is energized and as the inductor relay of stopping relay F reaches the stopping inductor plate UFP for the third floor, the contacts F1 open. These contacts in opening result in stopping of the elevator car at the third floor. A similar inductor plate is provided at each of the floors for which the elevator car A is to stop during up travel thereof.

If the elevator car A is to stop at the third floor during down travel thereof the winding of the stopping relay is energized and as the relay reaches the inductor plate DFP for the third floor, the contacts F2 open to produce a' stopping operation of the elevator car at the third floor. It will be understood that a similar inductor plate is provided for each of the floors at which the elevator car A is to stop during down travel thereof.

.Because of the large numberof. control circuits re-p quir'ed,'i't is' conventional practice to provide each ele vator car with a floor selector 16. This selector includes a plurality of rows of contact segments mountedon the insulating panel 16A. Only two rows of contact segments al to a5 and d1 to d5 are illustrated in Fig. 1. These contact segments are successively engaged during travel of the elevator car respectively by brushes aa and dd for the purpose of controlling the energizations of certain circuits. For example, if the elevator car A during down travel is to stop at the third floor in response to a car call, the brush aa engages the contact a3 shortly before the elevator car A reaches the third floor, to initiate a stopping operation thereof.

The brushes an and dd are mounted on a brush carriage 16C which is mounted for movement in accordance with movement of the elevator ,car, but at a greatly reduced rate. In the embodiment of Fig. 1, it is assumed that the carriage 16C has threaded engagement with a. screw 168 which is coupled to the shaft 13 through suitable gearing for rotation in accordance with movement of the elevator A. Consequently, as the 'elevator car A moves, the brushes mounted on the carriage 16C permit the energization of appropriatecircuits at various points of travel of the elevator car.

Although the driving motor 14 may be energized in various ways, it will be assumed that the control of this motor is of the type commonly referred to as avariable voltage control. In such a control, a direct current generator 17 has its armature 17A connected in a loop with the armature 14A of the motor. A series field winding 178 for the generator also may be included in this loop. The generator has a main field winding 17F which is connected for energization from the buses L1 and L2 through a reversing switch. This reversing switch includes contacts U2 and U3 of an up switch. When these contacts are closed, the field Winding is energized with proper polarity for up travel of the elevator car. Onthe other hand, when contacts D2 and D3 of a down switch are closed, the field winding is energized with proper polarity for down travel of the elevator car. The energization of the field windings is completed through a resistor R1 for slow speed operation of the elevator car or through make contacts VI of a speed relay for full speed operation of the elevator car.

The elevator car A is provided with a conventional spring-applied electromagnetically-released brake. This brake includes a brake drum 18D'which is secured to the shaft 13 for rotation therewith. A brake shoe 18C normally is biased against the brake drum by means of a spring (not shown). The brake is released upon energization of a brake coil 18B which cooperates with a magnetic armature 18A secured to the shoe 18C. The coil 18B is connected to the buses L1 and L2 for energization either through make contacts U1 or through make contacts D1 of the up switch U or the down switch D.

The speed relay V is connected for energization from the buses L1 and L2 through either of two paths. One of these paths includes make contacts U4 of the up switch, a limit switch 19 and the break contacts E1 of the slow-down relay. The limit switch 19 is a camoperated normally-closed switch which is opened as the elevator car nears its upper limit of travel.

The remaining path of energization comprises the make contacts D4 of the down switch, a limit switch 20 and the break contact E2 of the slowdown relay. The limit switch 20 may be cam operated. It is normally closed and is opened as the elevator car A nears its lower limit of travel.

As long as the elevator car A is running, the running relay M is energized. This relay can be energized only' as long as the make contacts DR1 of a door relay DR are closed. These contacts are closed only as long as all of the hoistway doors and car doors for the car A massierased. Sii'ch safety" provisions are well known in thelartl running relay M initially can be energized only if the breakqcontacts 78 -1 are closed to indicate that a call for service has been registered and if the break contacts 70T1 are closed to indicate that sufficient time has elapsed since the last stop of elevator car A to permit discharge or entry of passengers.

Assuming that the foregoing contacts associated with the runningrelay are closed, the relay may be energized initially through either of two paths. One of these paths is as follows:

L1, 70T1, 781, W1, F1, 21, U, M, DRI, L2

Since the up 'switchU is energized through this path, it follows that the elevator car will be conditioned for up travel. The limit; switch 21 is a normally-closed mechanically-operated switch which is opened as the elevator car A nears its upper limit of travel. When energized, the up switch U closes its make contacts US to establish a holding circuit around the contacts 70T1, 78-1 and The second path for initially energizing the running relay M may be traced as follows:

L1, 70T1, 78--1, X1, F2, 22, D, M, DRl, L2

Since the down switch D now is energized, it follows that the elevator car A is conditioned for down travel. The limit switch 22 is a mechanically-operated normallyclos'ed switch which is opened as the elevator car A nears its lower limit of travel. When it picks up, the down switch D closes its make contacts D5 to establish a holdingcircuit around the contacts 7(lT1, 78-1 and X1.

If theelevator car A is to be operated by a car atten'dant the contacts 78-1 and 70T1 may be replaced by a manually-operated switch which is closed by the car attendant when the car is to he moved from a floor at which it is stopped. However in a preferred embodiment of the invention the automatically-operated con tacts 78--1 and 70T1 are employed.

The slowdown relay E, the inductor relay F, and a holding relay G are energized in parallel from the buses L1 and L2 through make contacts M1 of the running relay M. To complete an energizing circuit for these relays E, F and G, one of the following conditions must be present: First, the make contacts T1 are closed to indicate that a car call is registered for a floor which the elevator'car A is approaching. Second, the contacts J1 are .closed to indicate that the elevator car A is conditioned to reverse at the next fioor reached by the elevator car. indicate that the elevator car A is conditioned to stop at a floor in answer to a registered floor call for such floor. Fourth, the contacts SE1 are closed to indicate that the elevator car A is approaching a floor for which a priority floor call has been registered for a long period of time.

When the holding relay G is energized, it closes its make contacts G1 to establish with the make contact M1 a holding circuit for the inductor relays E and F.

The direction of travel of the elevator car A is determined initially by an uppreference relay W and a down preference relay X. For the up preference relay W to be energized, the break contacts D6 must be closed (i. e. the down switch D is energized). The break contact-s X2 must be closed (i e. the down preference relay X is deenergized). The limit switch -23 also must be closed. This switch is normally closed and is opened as the elevator car A reaches its upper limit of travel, in this case, the sixth "floor.

"E ergiza nqn of the up preference relay W also requires closure of at least one of two sets of contacts. These include the break contacts 12 which "are closed when the elevatorcarA is notcon'ditioned to reverse at the nearest Third, the make contacts S1 are closed to.

floor in its direction of travel. Make contacts M2 are closed as long as the elevator car A is running.

The down preference relay X is energized if the break contacts U6 are closed (i. e. the up switch U is deenergized), the break contacts W2 are closed (i. e. the up preference relay is deenergized) and the limit switch 24 is closed. This limit switch is normally closed and is opened as the elevator car A reaches the lower terminal floor.

As long as the elevator car A is running, the make contacts M3 are closed to energize the non-interference relay 70T. When the elevator car A stops, the contacts M3 open to deenergize the relay. However, the relay 70,T has a substantial delay in dropout. This delay may be provided in any suitable manner as by connecting a resistor R2 across the relay coil. The time delay in dropout is selected to be suflicient to permit discharge of passengers from the elevator car A or entry of passengers into the elevator car 'A'after each stop.

It willjbe recalled that the door relay DR is connected across the buses L1 and L2 through contacts operated by each door associated with the elevator car A. If any of the doors is open, the contacts associated therewith are also open tojprevent energization of the door relay DR.

Energization of the high call reversal relay I prepares the elevator car A to reverse during up travel at the nearest floor. The high call reversal relay I may be energized if the elevator car A is conditioned for up travel (break contacts X3 are closed) and if certain other conditions are satisfied.

Thus, if at least a predetermined number of priority down floor calls are registered, make contacts 1T1 are closed. If at least a predetermined number of down floor calls are registered, make contacts 2CC1 are closed, or if at least a predetermined number of car calls are registered for the system, the make contacts MHCRI are closed. If in addition to one of these closures the make contacts 78U1 are closed to indicate no higher calls remain tobe answered (in some cases no higher car calls), the energizing circuit for the reversal relay I may be completed.

If the elevator car A is assigned to reverse at the highest down floor call in a low zone of floors, the make contacts Y1 are closed to complete with the contacts X3 an energizing circuit for the relay I which establishes a holding circuit through the contacts X3 and 13.

Figure 2 Figure 2 shows the call registration circuits for the elevator cars. Car call registration circuits are illustrated for the elevator cars A and B in the upper part of this figure. f

It will be recalled that the elevator car A is provided with a plurality of push buttons 10 to 60 for the purpose of registering car calls. Inasmuch as car call push buttons and associated circuits for the intermediate floors are similar, they are not illustrated in Fig. 2 for the third and fourth floors. Each of these push buttons has associated therewith a car call registering relay 10K to 6CR respectively. in this group only representative relays CR, Z'CR and IlCR are shown in Figs. 2A and 3A. The push buttons and call registration relays cooperate with four rows of contact segments located on the floor selector for the elevator car A. The contact segments al to a5 cooperate with the brush aa for the pulpose of initiating a stepping operation of the elevator car during down travel of the elevator car respectively at the first to fifth floors. The contact segments [12 to b6 cooperate with a brush bb for the purpose of initiating a stopping operation of the elevator car during up travel of the elevator car respectively at the second to sixth floors. A brush cc cooperates with a row of contact segments c2 to 06 and a brush dd cooperates with a'rowof contact segments d1 to d5 'for the purpose of cancelling registered car calls as they are answered respectively duriugdown travel and up travel of theelevator car. .It will be understood that for each contact segment, the numeral of the reference character designates the floor with which the contact segment is associated. Thus, the reference character a1 designates the contact segment for the first floor in the a row.

By reference to Fig. 2, it will be observed that when the car call push button 50 is pressed the car call registering relay SCR is connected therethrough across the buses L1 and L2. This relay closes its make contacts CR1 to establish a holding circuit around the push button. The contact segments a5 and b5 are connected through this set of contacts to the bus L1.

If the elevator car A is set for down travel, the make contacts X4 are closed. And if the elevator car is approaching the fifth floor, the make contacts M4 of the running relay also are closed. Consequently, as the elevator car nears the fifth floor, the brush aa engages the contact segment a5 to complete the following circuit for the car call stopping relay T:

L1, SCRl, a5, aa, X4, T, M4, L2

The energization of the relay T initiates a stopping operation of the elevator car A at the fifth floor.

As the elevator car A continues its approach toward the fifth floor, the contact segment 05 is engaged by the brush cc. As the elevator car comes to a stop, the break contacts MS of the running relay close to complete the following cancelling circuit:

L1, SCRI, SCRN, 05, cc, X5, M5, L2

The operating coil of the registering relay SCR and the cancelling coil SCRN are wound in opposition on a common core. Consequently, energization of the cancelling coil SCRN cancels the eifect of the operating coil and resets the registering relay SCR. Preferably, as the elevator car stops at the fifth floor, the brush aa passes slightly below the associated contact segment a5, however, the brush cc remains in engagement with the as sociated contact segment 05 as long as the elevator car A remains at the floor.

Next it will be assumed that the same call is registered for the fifth floor as the elevator car A travels up towards the fifth floor. Under these circumstances, the make contacts W3 and W4 of the up preference relay are closed. As the elevator car A nears the fifth floor, the brush bb engages the contact segment b5 to complete the following circuit:

L1, 5CR1, b5, bb, W3, T, M4, L2

The energization of the carcall stopping relay T results in the initiation of a stopping operation for the fifth floor.

As the elevator car A continues to approach the fifth floor, the brush dd engages the contact segment d5 to complete the following circuit:

L1, 5CR1, SCRN, d5, dd, W4, M5, L2

The energization of the cancelling coil SCRN resets the call registering relay SCR. During the stopping operation, the brush bb preferably passes slightly above the associated contact segment b5 Whereas the brush dd remains in engagement with the associated contact segment d5 as long as the elevator car A is at the fifth floor.

The car call registering circuits for all of the intermediate fioors are similar to those described for the fifth floor. For this reason and to conserve space, the intermediate floor circuits are illustrated in Fig. 2 only for the second and fifth floors.

The car call registering circuits for the upper terminal (sixth floor) may be similar to those employed for the intermediate floors. However, since the elevator car A stops at the sixth floor only during up travel, contact segments for the sixth floor need not be provided in the a and d rows. By reference to Fig. 2 it will be noted that 10 only contact segments b6 and c6 are provided for the sixth floor.

The car call registering circuits for the lower terminal I or first floor may be similar to those provided for the intermediate floors. Since the elevator car stops at the first floor only during down travel, contact segments for the first floor need not be provided in the b and 0 rows. For this reason, in the car call registering circuits only contact segments a1 and d1 are illustrated for the first floor.

The central part of Fig. 2 illustrates up floor call registering circuits. These circuits are operated by means of normally-open push buttons 1U to 5U common to all of the elevator cars which are located respectively at the firstv to fifth floors. Inasmuch as the push buttons and associated circuits for the intermediate floors are similar, they are not shown for the third and fourth floors. The push buttons have associated therewith up floor call registering relays lUR to SUR and cancelling coils lURN to SURN in a manner which will be clear from the discussion of the call registering relays and cancelling coils associated with the car call push buttons.

The up floor call registeringrelays 1UR to SUR and their cancelling coils are associated with contact segments for each of the elevator cars in the bank. For example, a row of contact segments e1 to 26, respectively for the first to sixth floors, is provided for the elevator car A and cooperate with a brush ee. A brush ff cooperates with a row of contact segments f1 to f5, respectively for the first to fifth floors for the elevator car A.

Let it be assumed that while the elevator car A is traveling up a prospective passenger waiting on the fifth floor presses the up floor call push button 5U to energize the up floor call registering relay SUR. This relay closes its make contact 5UR1 to establish a holding circuit around the push button.

Since the elevator car is assumed to be traveling up, the make contacts W5 of the up preference relay W are closed. It will be assumed further that the break con tacts MHCR3 (Fig. 2) of the first car-call quota relay MHCR are closed. (Although the elevator car B may employ similar contacts of the relay MHCR, in the embodiment illustrated the elevator car B does not employ such contacts but instead employs in the corresponding r. circuit break contacts HCRl of a second car-call quota relay HCR. In addition, the elevator car B circuit includes break contacts 3CC1 of a down call quota relay 3CC and break contacts 2T1 of a timed call relay 2T.) It is assumed that break contacts EMl of the second down service demand relay EM are closed. As the elevator car A nears the fifth floor, the brush ee engages the contact segment e5 to complete the following circuit:

L1, 511121, 25, 88, W5, MHCR3, s, EMl, L2

The energization of the floor call stopping relay S initiates the stop at the fifth floor. In response to movement of the car towards the fifth floor, the brush ff engages its contact segment f5. As slow down of the elevator car is initiated, the break contacts V6 close to complete the following cancelling circuit:

L1, 5UR1, SURN, f5, ff, W6, V2, L2

This resets the up floor car registering relay SUR. As the elevator car A comes to a stop, the brush ee preferably passes slightly above the contact segment 65. However, the brush ff remains in engagement with the contact segment f5 as long as the elevator car A remains at the fifth floor. By inspection of ,Fig. 2, it will be observed that the contact segment e5 is connected to the corresponding contact segments for the other elevator cars in the bank (such as contact segment BeS for the elevator car B). Similarly, the contact segment f5 is connected to corresponding contact segments (such as the contact segment Bf5) for the remaining cars of the bank. Consequently, operation of the push button 5U 11 is effective to stop the first up traveling elevator car which reaches the fifth floor and which is conditioned to acceptithe call at the fifth floor. l

The up floor call registering circuits for all of the intermediate floors are similar. Consequently, such circuits are illustrated in Fig. 2 only f'or' the second and fifth floors.

During up travel, the elevator cars also stop at the sixth floor if they reach such floor. 3 For this reason, a single contact segment (26 sufii ces for the sixth floor and is permanently connected to the bus Li. Since the elevat-or car A does not stop during up travel at the lower terminal or first floor, a contact segment in the 6 row is not required. With this exception, the call registering circuits for the first floor are similar to those described for the fifth floor.

The lower part of Fig. 2 illustrates the down floor call registering circuit for the elevator cars. Down floor calls are registered by operation of normally-open push buttons 2D to 6D for the second to sixth floors, respectively which have associated therewith down floor call registering relays 2BR to 6DR and cancelling coils ZDRN to eDRN. Each push button cooperates with its call registering rclay and its cancelling coil in the manner discussed with reference to the up floor call push buttons. Only relays 2DR, SDR and 6 DR in this group are shown in Figs. 2A, 3A and 4A.

For the elevator car A, a row of contact segments g1. to 35 cooperates with a brush gg and a row of contact segments h2 to h6 cooperates with a brush hh. Let it be assumed that the elevator car A while traveling down is approaching the fifth floor at which a down floor call has been registered by operation of the push button 5D. Such operation results in energization of the down floor call registering relay SDR to close the make contacts SDRI. Since the elevator car is traveling down, the make contacts X6 and X7 are closed. It will be assumed the brake contacts PDi, HCR3, H1, L2 and EMl are closed.

As the elevator car A nears the fifth floor, the brush gg engages the contact segment g5 to complete the following circuit:

Ll, SDRi, g5, gg, PDI, HCR3, X6 H1 and LZ1 in parallel, S, EM L2 The energization of the floor call stop relay 3 initiates a stopping operation of the elevator car A at the fifth floor. As the elevator car continues its approach, a brush hh engages the contact segment hS. The initiation of slow down of the elevator car A results in closure of the break contacts V2 to complete the following cancelling circuit:

Ll, SDRI, SDRN, I25, hh, X7, V2, L2

The energization of the cancelling coil resets the call registering relay SDR. Preferably, as the elevator car A comes to a stop, the brush gg passes slightly below the associated contact segment g5, but the brush hh remains in engagement with the associated contact segment 115.

The contact segment g5 is connected to corresponding contact segments (such as the contact segment BgS) of the remaining cars. Similarly, the contact segment 115 is connected to the corresponding contact segments (such as the contact segment BhS) for the remaining cars. Consequently, the first elevator car to approach the fifth floor while traveling down will answer a call registered by the call registering relay SDR.

The down floor call registering circuits for all of the intermediate floors are similar and may be traced readily in Fig. 2. The down fioor call registering relays for the upper terminal or sixth floor also may be similar. However, since the elevator car A does not stop at the sixth floor during down travel, the contact segment in the g row may be omitted for the sixth floor. Since the elevator car A always stops at the lower terminal floor, a single first floor cont-act segment g1 may be provided for the til) '12 elevator car A and this contact segment may be perma istl se t d t tbs b A normally-open mechanical switch 28 may be camoperated to closed position as the elevator car A approaches the upper and lower terminal floors to shunt the contacts EMIJ Figure 3 As shown in Fig. 3, the presence of the elevator car A in a low zone of floors is determined by a zone relay 'LZ which is connected between a brush if and the bus L2. The brush coacts with contact segments jl to f4 for the first to fourth floors which constitute a low zone. These contact segments are located on the floor selector. The brush if has a length sufficient to bridge adjacent contact segments.

In Fig. 3, a call circuit 30 for car A is provided which has two functions. This circuit energizes a call relay 78 when no call is registered in the elevator by the car call push buttons for the elevator car A or by any floor call push button. in addition, the call circuit 30 energizes the call above relay 78U as the elevator car during up travel nears the highest floor for which a down floor call on a car call is registered provided no up floor call is registered for such floor or a higher floor.

The calltabove circuit 30 includes break contacts for all of the floor call registering relays and for all of the elevator A car call registering relays arranged in the order of the floors. This circuit may be traced as follows:

L1, 6CR2, 6DR2, SURZ, SCRZ, SDRZ, 4UR2, 4CR2, 4DR2, 3UR2, ECRZ, SDRZ, ZURZ, ZDRZ, 2CR2, iCRZ, IURZ, 78, L2

By inspection of this circuit, it will be observed that as long as a call is registered by the car call push buttons for the elevator car A or by the floor call push buttons the relay 78 is deenergized.

The call circuit 30 has associated therewith a row of contact segments k1 to k5 which are engaged successively by the brush kk as the elevator car A moves. The contact segments are so located relative to the call circuit 30 that each contact segment is placed below all break contacts of the call circuit which require travel of the elevator car A above such contact segment. Thus, the contact segment k5 is connected to the call circuit between the contacts SURZ and SCRZ. The contact segment k4 is connected between the contacts 4UR2 and 4CR2. The location of the remaining contact segments similarly may be ascertained by reference to Fig. 3. It will be noted that the relay 78U is connected between the brush kk and the bus L2 through make contacts W7 of the up preference relay W.

in certain cases, it is desirable to. prevent registered calls from affecting the call circuit 38. For example, it may be desirable under some conditions to prevent registered floor calls from affecting the operation of the relay 78U and 78. To this end, make contacts of the first carcall quota relay MHCR are provided for the purpose of shunting the break contacts of the floor call relays. When the relay MI -ICR is energized, the contacts MHCR4. to MHCRS close to shun; contacts SURE to ZURZ and um to 2.1m.

Although contacts of the relay MHCR similarly may be associated with the call circuit B30 for the elevator car B, in a preferred embodiment of the invention a separate relay HCR has make Contacts HCR4 to HCR8 associated with the call circuit 133% to shunt contacts SURS to 2UR3 and 6DR3 to 2DR3, as clearly shown in Fig. 3.

Make contacts EMS to EM6 and USEl to USES are arranged to shunt contacts of the up floor call registering relays in the, call circuits 30 and i330 for floors above the first floor.

The down call. uota relays ZCC to SCC indicate the presence of predetermined: service demands. As shown in Fig. 3, the quota relays preferably are energized in accordance with the number of. registered down floor calls. The energization of the relays is dependent on the condition of a parallel circuit having five parallel arms. Each arm contains a suitable resistor and a set of make contacts of a separate one of the down floor call registering relays. The resistors are so proportioned that a predetermined number of down floor calls must be registered before the relays will pick up.

The number of calls to which the down call quota relays respond depends on the number of floors of the elevator system, the number of elevator cars and other factors of the particular installation. For present purposes it will suffice to assume that the relays 2G0, 300, 4G0 and SCC pick up respectively in response to registration of two, three, four and five down floor calls.

The timed call relays 1T, 2T, 3T and 4T compute the number of registered down floor calls which have been registered for more than a predetermined time. To this end the relays are energized through a parallel circuit having five parallel arms. Each of the arms includes a set of break contacts 2DRT1 to 6DRT1. These contacts close respectively when down floor calls have beenregistered respectively at the second to sixth floors for more than a predetermined time.

The resistors RT1 to RTS in the parallel circuit and the timed call relays IT to 4T are so selected that each of the time call relays picks up in response to registration of at least a predetermined number of down floor calls for more than a predetermined time. For present purposes, it will suffice to assume that the relay 1T picks up if one or more down floor calls hasbeen registered for more than the predetermined time. The relay 2T picks up only if it is energized through two or more of the resistors RT1 to RTS to indicate that two or more timed out or priority down floor calls are registered. In an analogous manner the relays 3T and 4T pick up in response to the presence of at least respectively three and four timed out or priority down floor calls.

The down call quota relays ZCC to ECG and the timed call relays IT to 4T are employed for computing the demand for elevator service in the down direction and for controlling the operation of the elevator system in accordance with such demand. It will be recalled that closure of the make contacts 1T1 or 2CC1 (Fig. 1) pre pares the reversal relay I for energization as the elevator car A when traveling up approaches the farthest floor for which a call is registered provided such call is not an up floor call. In Fig. 2 opening of either the break contacts 2T1 or the break contacts 3CC1 prevents response of the elevator car B to up floor calls. of the make contacts 2T2 or 3CC2 energizes the modifying relay USE. The pickup of the down call quota relay 4C0 or of the timed call relay 3T indicates a still further increase in the demand for down service. The pickup of either of these relays is accompanied by closure of the make contacts 4CC1 or 3T1 to energize the first down service relay DSE (Fig. 3). As will be pointed out in connection with Fig. 4 the energization of this relay increases the capacity of the elevator system to handle down traffic.

A still further increase in the demand for down service is accompanied by pickup of the down call quota relay SCC or of the timed call relay 4T. Pickup of either of these relays is accompanied by closure of the make contacts CC1 or 4T1 to energize a second down service demand relay EM. Pickup of this relay results in opening of the break contacts EMl (Fig. 2) and similar contacts for the other elevator cars of the system to prevent energization of the floor call stopping relays. As will be pointed out in the discussion of Fig. 4, during the energization of the second down service demand relay EM the elevator cars can respond to down floor calls only if such In Fig. 3 closure The performance of the elevator system also is controlled by the first car call quota relay MHCR (Fig? 3) and the second car call quota relay HCR. These relays are connected in series with each other and in series with break contacts 2CC3 and 1T3 for energization through a parallel circuit containing a plurality of arms. Each of the arms includes a set of make contacts of a separate one of the car call registering relays and a resistor. In order to conserve space only two arms are illustrated for each of the elevator cars A, B and C. Thus for the elevator car A one of the arms contains break contacts 1CR3 and a resistor R8. A second arm contains break contacts 6CR3 and a resistor R13. It will be understood that a similar arm is provided for each of the car call registering relays associated with each of the elevator cars.

The first car call quota relay MHCR is designed to pick up when energized through at least a predetermined number of the parallel arms of its energizing circuit. For present purposes it will be assumed that this relay is picked up only if energized through at least three arms of the parallel circuit.

The second car call quota relay HCR is designed to pick up when energized through a larger number of arms of the parallel circuit. For the purpose of discussion it will be assumed that this relay is designed to. pick up only if energized by at least six arms of the parallel circuit. The pickup point of either of the relays may be adjusted in any suitable manner as by connecting an adjustable resistor thereacross. As a specific example, an adjustable resistor RH is illustrated in parallel with the second car call quota relay HCR.

If desired, each of the parallel arms through which the relays HCR and MHCR are energized may include make contacts of the up preference relay for the associated elevator car. If such an expedient is adopted, the relays are energized in accordance with the number of car calls registered by passengers desiring to travel in the up direction. However for present purposes it will be assumed that such contacts of up preference relays are not employed.

Figure 4 Fig. 4 shows circuits for the auxiliary high floor-call relay Y which controls reversal of an elevator car A when it is assigned to the low zone. In addition, Fig. 4 shows circuits for the high zone car relay H which assigns the elevator car A to the high zone and for the low zone car relay L which assigns the car A to the low zone. These relays are controlled by a first selection relay 300 and a second selection relay 301 which are common to all of the elevator cars.

The transfer of the elevator system to down peak operation is initiated by closure of make contacts DSE2 and DSE3 of the down service relay DSE (Fig. 3) which is common to all of the cars.

Referring to the auxiliary high floor-call relay Y in greater detail, it will be noted that this relay is connected between the brush 51 and the bus DC only when the make contacts L4 of the low zone car relay are closed (such closure indicates that the elevator car A is assigned to the low zone). The buses DC+ and DC are connected respectively to the buses L1 and L2 when the con-.

break contacts of the floor registering relays requiring further travel of the elevator car in the up direction are located between the contact segment and the bus DC+..' Thus, all of the break contacts are located between thecontact segment 2m and the bus DC+. As a further example, the contact segment 3m is connected between the break contacts 3DR5 and 4DR 5. This means that the-only contacts 4DR5 requiring travel of the elevator car above the third floor are between the contacts 3m and the bus DC+. Since the fourth floor is assumed to be the top floor of the low zone, the contact segment 4m for the fourth floor is connected directly to the bus DC+.

When the down service relay DSE operates to place the system on down peak operation, its make contacts DSE3 close to prepare a motor SM for operation. This motor may .be of any desired type. For example, it may be a stepping relay which has a plurality of commutator switches. In the present embodiment it will be assumed that the motor SM is an alternating-current motor having an armature SMA and a field winding SMF. When this motor is energized, it rotates a commutating movable contact 79 to engage successively contacts 79A, 79B and 79C. One of these contacts is provided for each of the elevator cars of the bank. For present purposes, itwill be assumed that elevator cars A, B and C are in the bank and that the three contacts 79A, 79B and 79C are associated therewith.

The motor SM also operates a movable contact 81 which similarly is associated with contacts 81A, 81B and 81C.

The energization of the motor SM may be completed through any one of the three parallel circuits, one for each of the elevator cars. Thus, if the elevator car A is not assigned to the low zone, the break contacts L5 i are closed. If the elevator car A is not assigned to the high zone, the break contacts H2 are closed. When the elevator car A in its down trip reaches a point such as 5 feet below the second floor, the mechanical switch P2 is closed to complete an energizing circuit for the motor SM through the contacts DSE3. Each of the three elevator cars A, B and C may similarly control the energization of the motor SM. The motor SM and associated circuits select the order in which the elevator cars are assigned to the high and low zones.

Assignments of the elevator cars to the high zone or to the low zone are cancelled upon arrival of the elevator cars at a predetermined point such as adjacent the second floor carrying down travel. At this point the mechanical switch P1 is opened by its cam 55 to terminate any assignment of the associated elevator car A. The mechanical switch recloses subsequently such as at a point 5 feet below the second fioor to prepare the high-zone car relay H and the low-zone car relay L for subsequent energization. At the same time the motor SM starts to advance or move the movable contacts 79 and 81 for the purpose of finding an elevator car ready for assignment.

The movable contact 81 controls, in part, the energization of the selection relays 300 and 301. If the make contacts 300-1 and the break contacts 301-1 of these relays are closed, and if the movable contact 81 is in engagement with the fixed contact 81A, the high-zone car relay H will be energized and will establish a holding circuit for itself through its make contacts H3.

On the other hand, if the break contacts 300-3 and the make contacts 301-3 are closed at the time the movable contact 81 engages the fixed contact 81A, an energizing circuit is established for a low-zone car relay L and this relay establishes a holding circuit for itself through its make contacts L7.

When the elevator car A reaches the lower terminal floor, the make contacts W10 of the up preference relay close to maintain the energization of either of the relays H or L despite subsequent opening of the mechanical switch P1. 7

The. selection relays 300 and 301 are employed for the purpose of assigning the elevator cars in a predetermined sequence to the high and low zones. In the present case, successive elevator cars available for assignment are assigned alternately to the high and low zones of floors;

Let it be assumed initially that the selection relays 300 and 301 are deenergized. As the elevator car A nears the lower terminal floor and is made available'for assignment to one of the zones of floors, the motor SM operates the movable contact 79 to scan the fixed contacts associated therewith. When the movable contact 79 engages the contact 79A associated with the car A, the following energizing circuit for the first selection relay 300 is established:

DC+, 301-7, 79, 79A, L8, H5, 301-5, 300, R5, DC-

The resistor R5 limits the flow of current under certain conditions wherein the resistance of associated parts of the circuit is reduced.

As a result of its energization, the first selection relay 300 closes its make contacts 300-1 to establish an energizing circuit for the high-zone car relay H. This assigns the car A to the high zone.

At the same time, the relay 300 closes its make contacts 300-5 to establish an energizing circuit for the second selection relay 301 as follows:

DC+, 301, 300-5, 300, R5, DC

The high zone car relay H is conditioned to operate slightly in advance of the relay 301 and opens its break contacts H5 to isolate the relays 300 and 301 from the movable contact 79.

Let it be assumed next that the elevator car B is approaching the lower terminal floor and that it is conditioned for assignment to one of the zones While the selection relays 300 and 301 remain energized. As the elevator oar B nears the lower terminal floor, the motor SM again is operated to move the movable contacts 79 and 81. When the movable contact 79 reaches the fixed contact 79B, a shunting circuit is established for the selection relay 300 which may be traced from one terminal of the relay coil through the make contacts 300-5, the make contacts 301-6, the break contacts EH5, the break contacts BL8, the fixed contact 793, the movable contact 79 and the make contacts 301-8 to the remaining terminal of the relay coil. As a result of the deenergization of the first selection relay 300,-the break contacts 300-4 close to complete the following circuit for the low-zone car relay for the car B:

130+, BPl, BL, EH4, soc-4, 301-4, 81B, 81, DC-

Inasmuch as the contacts 300-5 and the contacts BL8 now are both open, the second selection relay 301 is deenergized.

From the immediately preceding discussion, it follows that the selection relays 300 and 301 are effective for assigning successive available elevator cars alternately to the high and low zones of floors.

A system for assigning elevator cars alternately to different zones in a manner similar to that discussed for Fig. 4 is set forth in my copending application, Serial No. 264,036, filed December 29, 1951, which is now Patent 2,688,383.

The floor call timing relays 2DRT to 6DRT are employed for the purpose of measuring the duration of registration of each down floor call. For example, the fioor call timing relay 2DRT for the second floor is connected across the buses L1 and L2 through break contacts 2DR5 of the down floor call registering relay 2DR for the second floor. When a down floor call is registered for the second floor the break contacts ZDR open to deenergize the floor call timing relay ZDRT. This relay has a substantial time delay in dropout. This time delay may be provided in any suitable manner. For purposes of illustration it will be assumed that a resistor 2R7 is connected across the relay for the purpose of delaying its dropout. For present purposes it will be assumed that the delay in dropout of the relay is of the order of 40 seconds. Each of the remaining floor call timing relays 3DRT to. 6DRT similarly is associated with break contactsof the down floor call registering relay for the associatedafloor.

It will be recalled that break contacts 2DRT1 to 6DRT1 of the floor call timing relays control the energization of the timed call relays IT to 4T (Fig. 3). In addition, the floor call timing relays have break contacts 2DRT2 to 5DRT2 (Fig. 4) which are employed for the purpose of controlling the energization of a timed floor call stopping relay SE for the elevator car A and similar relays for the remainder of the elevator cars employed in the system.

By inspection of Fig. 4 it will be noted that the elevator car A is provided with a row of contact segments n2 to 115 which may be mounted on the floor selector for the elevator car A. Each of these contact segments is connected to a similar contact segment for each remaining elevator car of the system. A brush nn is associated with the row of contact segments for the elevator car A. As the elevator car A moves from the sixth floor to the lower terminal floor, the brush nn successively engages the contact segment n5 to n2 as the elevator car approaches respectively the fifth to sec-nd floors. 7

Each of the contact segments such as n2 is connected to a conductor LC through break contacts 'such .as 2DRT2 of the floor call timing relay associated with the. same floor. The brush nn is connected to the bus DC- through the timed floor call stopping relay SE and make contacts X8 of the down preference relay X. The conductor LC is connected to the bus L1 through make contacts EM11 and DSE2. Consequently, if the contacts DSE2 and EM11 are closed and the elevator car A is traveling in the down direction, the timed floor cal-l stopping relay SE will be energized as the elevator car A approaches each floor for which a down floor call has been registered for more than a predetermined time.

Figure In Fig. 5 circuits are illustrated for expediting the travel of an elevator car carrying a passenger who has been unduly delayed in reaching his destination.

The circuits of Fig. 5 include two timing relays TA and TB. Each of these relays has a substantial time delay in dropout which may be provided in any suitable manner as by connecting a resistor across the relay. It will be noted that the first timing relay TA is connected across the buses L1 and L2 through break contacts TB1 of the second timing relay. The second timing relay TB is connected across the buses through make contacts TAV of the first timing relay TA. Consequently, the timing relays TA, TB drop out and pick up at timed intervals.

The timing relays have break contacts TA2 and make contacts TBZ connected in series with make contacts CR4 of the car call registering relay for the first floor for the purpose of controlling the energization of a stepping relay SST. The stepping relay SST has a pair of contact arms 40A and 40B which are displaced from each other angularly about an axis 180. These arms coact with a semicircular row of contact segments 40a to 40g. The arms are shown in their initial positions wherein the arm 40A engages the contact segments 40a. The contact arm 40B has just left the contact segment 40g. The contact segments 46!) to 40g all are connected to the bus L2 through break contacts SSTl of the stepping switch and the winding of the stepping switch. For each energization of the winding of the stepping switch the contact arms are advanced through an angular distance corresponding to the angular distance between adjacent contact segments. At the contact arm 40A finally leaves the contact segment 40g the contact arm 40B engages the contact segment 46a. Such stepping switches are well known in the art.

The contact arms 40A and 40B are connected to the bus L1 through break contacts 1CR5 associated with the car call relay for the first floor.

18 The stepping switch also has a second pair of arms 40AA and 40BB which are rotated with the first set of contact arms 40A and 403. The second set of arms is associated with a second row of contact segments of which only the contact segment 4tiee is connected to the bus L2 through an auxiliary relay PT and break contacts .W9 of the up preference relay. The contact arms 40AA and 40BB are connected directly to the bus L1. It will be noted that the auxiliary relay PT has make contacts PTl which cooperate with the break contacts W9 to establish a holding circuit for the relay.

The auxiliary relay PT has make contacts PT2 for controlling in part the energization of the pass relay PD. This'relay has break contacts PDl (Fig. 2) for control ling in part the energization of the floor call stopping relay S. In addition, make contacts PD2 (Fig. 5) establish an independent energizing circuit for the step winding of the stepping switch. Make contacts PD3 cooperate with the break contacts W9 to establish a holding circuit for the pass relay PD.

The initial energization of the pass relay PD requires closure not only of the break contacts W9 and the make contacts PT2 but also of one of the sets of contacts 2CC4 or PBl. The break contacts 2CC4 remain closed as long as the registered down floor calls remain below a predetermined number. For present purposes it will be assumed that the break contacts 2CC4 remain closed as long as less than two down floor calls are registered.

The make contacts PB1 close when another elevator car passes the elevator car A.

The passing of one elevator car by another elevator car is detected by the relative position relay PB and by similar relays for the other elevator cars of the system. Each of the elevator cars is provided with a row of contact segments which may be mounted on the associated floor selector. For example, the elevator car A has a row of contact segments 12 to p6 which have two brushes ppl and p112 associated therewith. The brush ppl is connected to the bus L2 through break contacts M6 of the running relay M, relay PB and make contacts X9 of the down preference relay. When the relay PB picks up it establishes a holding circuit for itself through its make contacts PBZ and the make contacts X9.

The brush pp2 is connected to the bus L1 through break contacts P133 of the relative position relay. During down travel this brush leads the brush ppl by one floor. For example, if the elevator car A is at the fifth floor, the brush pp engages the contact segment p5 and the brush ppZ engages the contact segments p4. Each of the contact segments 22 to p6 is connected to each corresponding contact segment for the remainder of the elevator cars. As will be shown below when the elevator car A is set for down travel while stopped at a floor and is passed by another car such as the elevator car B traveling down, the relative position relay PB will be energized unless the elevator car B has its relay BPB energized at the time.

OPERATION In order to assure a full understanding of the invention, certain typical operations of the elevator system now will be considered. First, it will be assumed that the elevator cars are parked at the lower terminal floor and that a passenger enters the elevator car A at the lower terminal floor for the purpose of proceeding to the fifth floor.

The doors of the elevator cars may be of the manuallyopened, spring-closed type or may be of conventional power-operated design. Upon entering the elevator car A, the passenger presses the car call push button 50 (Fig. 2) to energize the associated car call registering relay SCR. This relay closes its make contacts 5CR1 to establish a holding circuit around the push button. The relay'also opens its break contacts 5CR2 (Fig. 3) to deenergize the relays 78U and 78. Inasmuch as the elevator car A is at the lower terminal floor, it will be understood that the up preference relay W is energized and picked up.

contacts U1 to release the elevator brake.

. operation.

The car call registering relay also closes its make contact CR3 (not shown in Fig. 3 but similar to 6CR3).

However, it will be recalled that the energization of the relays MHCR and HCR through a single one of the resistors R8 to R13 is insufficient to pick up either relay.

Inasmuch as the relay 78 is now dropped out, the contacts 78-1 (Fig. 1) are closed. It will be assumed also that the elevator car A has remained at the lower terminal floor for a time sufiicient to result in closure of the break contacts 70T1. Consequently, upon closure of the doors, the door relay DR closes its make contacts DR1 to complete the following circuit:

' L1, 7QT1, 78-1, W1, F1, 21, U, M, DR1, L2

Upon energization, the up switch U closes its make Contacts U2 and U3 close to energize the generator field winding 17F with proper polarity for up travel of the elevator car. Contacts U4 closes to complete the following energizing circuit for the speed relay V:

L1, U4, 19, E1, V, L2

The speedy relay closes its make contacts V1 to shunt the resistor R1 and conditions the elevator car for full speed The speed relay V also opens its break con- .tacts V2 (Fig. 2) without immediate effect on the system operation.

Continuing with the operation of the up switch U, the energized up switch closes its make contacts US to establish a holding circuit around the contacts 70T1, 78-1 'and W1. Break contacts U6 open to prevent energization therethrough of the down preference relay X.

The elevator car A now accelerates in the up direction for the purpose of carrying the passenger to the fifth floor.

Itwill be recalled that the running relay M also was energized. .As a result of its energization, the running relay closes its make contacts to prepare the relays G, E and F for subsequent energization. The make contacts M2 close to maintain the energization of the up preference relay despite subsequent opening of the break contacts J2. Make contacts M3 close to energize the non-interference relay 70T. The non-interference relay opens its break contacts 70T1 but such opening has no immediate effect on the operation of the system.

Referring to Fig. 2, the running relay M closes its make contacts M4 and opens its break contacts M5. Such contact operations have no immediate effect on the operation of the-system.

Asthe elevator car nears the fifth floor, the brush kk (Fig. 3) 'engages the contact segment k5 which is positionedabove the open break contacts 5CR2. Consequent ly, the call-above relay 78U is energized through the circuit:

L1, 6CR2, 6DR2, SURZ, k5, kk, W7, 78U, L2

The relay 78U closes its make contacts 78U1 (Fig. 1). Under the assumed conditions, the energization of the relay 78U has no immediate effect on the operation of the system.

However, the approach of the elevator car A towards .the fifth floor brings the brush bb (Fig. 2) into engagement with the contact segment b5 to energize the car call stopping relay T through the circuit L1, 5CR1, b5, bb, W3, T, M4, L2

The car call stopping relay closes its make contacts T1 (Fig. 1) to energize through the contact M1 the three relays G, E and F in parallel. The relay G closes its make contacts G1 to establish a holding circuit around the contacts T1.

The energization of the inductor slowdown and stopping relays E and F prepares these relays for subsequent operation. As the elevator car A nears the fifth floor, the inductor slowdown relay E reaches the inductor plate UEP for the fifth floor which completes a magnetic circuit resulting in the opening of the normally-closed contacts E1. Such opening deenergizes the speed relay V. As aresult of the deenergization of the speed relay V, make contacts V1 open to introduce the resistor R1 in series with the generator field winding 17F. The resulting decrease in the output of the generator slows the elevator car A to a landing speed. Closing of break contacts V2 (Fig. 2) has no immediate effect on the system.

As the elevator car A- slowly approachesthe fifth floor, the stopping relay F reaches the inductor plate UFP for the fifth floor. This completes a magnetic circuit which re- In opening the contacts F1 deenergizes the up switch U and the running relay M.

The up switch U now opens its make contacts U1 to apply the elevator brake. Contacts U2 and U3 open to deenergize the generator field winding and the elevator car now stops accurately at the fifth floor. Opening of the make contacts U4 and U5 and closure of the break contacts U6 have no immediate effect on the operation of the system.

The running relay M opens its make contacts M1 to deenergize the relays G, E and F. The relay G opens its make contacts G1. Opening of the make contacts M2 has no immediate effect on the system operation. Make contacts M3 open to deenergize the non-interference relay 70T. This relay now starts to time out. Opening of make contacts M4 (Fig. 2) has no immediate effect on system operation.

Referring to Fig. 2, it should be noted that as the elevator car A continues its approach toward the fifth floor, the brush dd engages the contact segment d5. When the running relay drops out to close its break contacts M5, the following cancelling circuit is completed.

L1, 5CR1, SCRn, d5, dd, W4, M5, L2

Consequently, the car call registering relay 5CR is reset. As the car comes to a stop, the brush bb passes slightly above the associated contact segment b5.

The resetting of the call registering relay SCR opens the make contacts 5CR1. In addition, the break contacts 5CR2 (Fig. 3) reclose to complete an energizing circuit for the call relay 78 (Fig. 3). The make contacts SCRS open to interrupt the partial energization of the relays MHCR and HCR.

The call relay 78 as a result of its energization opens its break contacts 781 (Fig. 1). Consequently, when the non-interference relay 70T times out and recloses its break contacts 70T1, the up switch U and the running relay M can not be energized until a call is registered from one of the floors or in the elevator car A to close the contact 78--1.

Next it will be assumed that as the elevator car A was leaving the first floor in the preceding example, a prospective passenger at the second floor registered an up floor call by operation of the up floor call push button 2U (Fig. 2). Such operation energizes the up fioor call registering relay 2UR which closes its contact 2UR1 to establish a holding circuit around the push button. In addition, the registering relay opens its break contacts 2UR2 in the call circuit 30 (Fig. 3) and similar contacts,

,such as the contact 2UR3, in the call circuits for the remaining elevator cars in the bank. Since the registration of the car call for the fifth floor in the elevator car A has deenergized the relays 78U and 78, opening of the contacts 2UR2 has no effect thereon. However, the opening of the contacts may affect the remaining elevator cars of the system. For example, the opening of the break contacts 2UR3 deenergizes the relay 78 for the car B and permits operation of such elevator car.

As the elevator car A nears the second floor, the brush ee engages the contact segment e2 to establish the circuit:

L1, 2UR1, e2, ee, W5, MHCR3, S, EMl, L2 

